Radio system adjustment with TPMS and smart entry system

ABSTRACT

A tire pressure monitoring system includes tire sensors mounted in, on or adjacent respective tires of the vehicle, LF antennas mounted on the vehicle, and an ECU. Each tire sensor is configured to transmit an RF signal and to detect an LF field. Each antenna is configured to transmit an LF field to wake up the tire sensors. The ECU is in communication with the antenna, the tire sensors and a radio configured to receive AM broadcast signals. The ECU can communicate with the radio to inhibit speakers in communication with the radio from emitting sound while each LF field to wake up the tire sensors is being transmitted.

This application claims the benefit of U.S. provisional patentapplication Ser. No. 61/354,809, filed Jun. 15, 2010, which isincorporated by reference in its entirety herein.

BACKGROUND

Exemplary embodiments disclosed herein are directed to tire pressuremonitoring systems for vehicles that can also include keyless entrysystems. Many cars today apply SMART entry by employing 125 KHz lowfrequency (“LF”) antennas in many locations around the vehicle tolocalize a SMART search field. For example, an LF antenna can mount to adriver door handle to search an area surrounding the driver door for aportable transmission/reception unit, e.g. a key fob, for keyless entryto the vehicle. These LF SMART search fields are highly controlled, suchthat specific search patterns can be realized.

By regulation, all vehicles in the United States must include a tirepressure monitoring system (“TPMS”). In a known TPMS, an LF antenna ismounted in each wheel well such that a TPMS control unit can trigger, orwake up, each TPMS sensor, which are each located in a respective tire,via the LF antenna. The TPMS control unit sends a signal to the LFantenna to transmit an LF field to wake up the TPMS sensor. The TPMScontrol unit can receive a near instantaneous response such that thetire pressure for each wheel is known in seconds and can be presented ona display in the vehicle cabin for the vehicle operator.

Like the known SMART entry systems, known TPMS employ 125 KHz LFantennas. For a vehicle including both SMART entry and TPMS, up to tenindividual LF antennas can be required on the vehicle. Both the TPMSsensors and the SMART entry fobs reply to a receiver in the vehicle withan RF signal around 315 MHz. Both systems are slightly offset from thisfrequency for independent operation, but the frequencies are closeenough that similar antennas can be used to receive the signal.

Combining SMART entry and TPMS to reduce the number of LF antennas onthe vehicle can result in problems. Known combined SMART entry and TPMSmay fail to provide tire pressure data to the operator at the moment (ornearly instantaneously after) the ignition for the vehicle is turned ON.This is due to the fact that localization of the tire sensors can bedifficult when the antenna that is used to wake up each tire sensor isnot mounted within a respective wheel well. Additionally, since both thetire sensors and the fobs wake up upon detecting an LF field, the fobmay respond by sending a signal to a receiver in the vehicle when the LFfield was intended to only wake up the tire pressure sensors, and viceversa. This can result in an undesirable drain on the power source forthe tire pressure sensors and the fob.

Moreover, providing tire pressure data at ignition ON can presentissues. Waking up a tire sensor without moving the tire can present aproblem because the tire sensor can be located at nearly an infinitenumber of positions when a vehicle is parked, and some of thesepositions may not be conducive for detecting an LF field generated froman antenna that is not located within the wheel well. Moreover,transmitting an LF field strong enough to wake up tire sensors mayresult in a broadcast AM receiver, which is typically connected with avehicle radio, picking up the LF field such that undesirable sound isemitted from a speaker connected with the radio. Moreover, problems mayarise localizing one or more of the tire sensors when one of the SMARTentry and TPMS antennas is mounted on a vehicle door and thedoor-mounted antenna emits an LF search field to wake up the tiresensors. Moreover, recognizing tire sensor locations when in themanufacturing facility can also present issues.

SUMMARY

An example of a vehicle entry/tire pressure management system that canovercome at, least one of the aforementioned shortcomings includes aleft front tire sensor, a left rear tire sensor, a right front tiresensor, a right rear tire sensor, a first low frequency (“LF”) antenna,a second LF antenna, a third LF antenna, a fourth LF antenna, and anECU. Each tire sensor is mounted in a respective tire of the vehicle.Each LF antenna is mounted on the vehicle and is configured to transmitan LF field to wake up two of the tire sensors. Two of the LF antennascan also be configured to transmit a SMART entry LF search field to wakeup a portable transmission/reception unit for keyless entry of thevehicle. The ECU is in communication with the tire sensors, via areceiver, and the LF antennas. The ECU is configured to receiveidentification signals from the respective tire sensors and to determinelocations of the respective tire sensors based on which antenna woke upthe tire sensor transmitting the respective identification signal andwhether the respective identification signal matches other receivedidentification signals.

A method of localizing tire sensors on a vehicle to present data to anoperator of the vehicle includes transmitting an LF tire sensor wake upsignal from four tire antennas to wake up tire sensors located in tireson the vehicle. Each antenna is configured and positioned on the vehiclewith respect to the tire sensors to transmit its respective tire sensorwake up signal to wake up two tire sensors. Three of the antennas arealso configured to transmit an LF fob wake up signal to wake up aportable transmission/reception unit for keyless entry of the vehicle.In response to receiving the tire sensor wake up signals, the method oflocalizing tire sensors further includes transmitting RF signalsincluding an identification signal from tire sensors to an RF receiveron the vehicle. The method further includes receiving the RF signalsincluding the identification signal via the RF receiver into the ECU andcomparing the received identification signals. The method furtherincludes determining locations of the respective tire sensors based onwhich antenna woke up the tire sensor transmitting the respectiveidentification signal and whether the received respective identificationsignal matches other received identification signals. The method furtherincludes presenting tire data on a display at ignition ON and prior tomovement of the tires based on the received RF signals and thedetermined locations of the respective tire sensors.

Another example of a vehicle entry/tire pressure monitoring system for avehicle that can overcome at least one of the aforementionedshortcomings includes an ECU, tire sensors mounted in, on or adjacentrespective tires of the vehicle, a portable transmission/reception unitconfigured to be carried by an operator of the vehicle, and an antennamounted on the vehicle and in communication with the ECU. Each tiresensor is configured to transmit an RF signal. The portabletransmission/reception unit can transmit RF signals for controllingoperations of the vehicle including unlocking doors of the vehicle. Theantenna is configured to transmit an LF tire sensor wake up field towake up the tire sensors. The tire sensor wake up field includes aunique header format. The tire sensors only fully wake up upon receivingthe unique header format.

A method for operating a vehicle entry/tire pressure monitoring systemincludes transmitting an LF field from an antenna mounted on a vehicle.The LF field includes a unique header format. The method furtherincludes partially waking up a tire sensor to process the unique headerformat and partially waking up a portable transmission/reception unit toprocess the unique header format. The tire sensor is disposed in a tireof the vehicle. The portable transmission/reception unit communicateswith an ECU on the vehicle to control operations of the vehicle. Wherethe unique header format matches a tire pressure sensor wake up header,the method for operating a vehicle entry/tire pressure monitoring systemalso includes fully awakening the tire sensor. Where the unique headerformat data matches a portable transmission/reception unit wake upheader, the method further includes fully awakening the portabletransmission/reception unit.

Another example of a vehicle entry/tire pressure monitoring system for avehicle that can overcome at least some of the aforementionedshortcomings includes an ECU, LF antennas mounted on the vehicle andbeing in communication with the ECU, and tire sensors mounted in, on oradjacent respective tires of the vehicle. Each LF antenna is configuredto transmit an LF tire sensor wake up field and a SMART entry LF searchfield to wake up a portable transmission/reception unit for keylessentry of the vehicle tire sensor. Each tire sensor includes a two-axisreceiver antenna and an RF transmitter configured to transmit an RFsignal. Each two-axis receiver antenna is configured such that a firstaxis of the two-axis antenna is configured to detect a respective LFfield transmitted by one of the LF antennas and a second axis of thetwo-axis antenna is configured to detect a respective LF fieldtransmitted by another of the LF antennas.

Another example of a vehicle system that can overcome at least one ofthe aforementioned shortcomings includes tire sensors mounted in, on oradjacent respective tires of the vehicle, LF antennas mounted on thevehicle, an RF receiver mounted on the vehicle, a memory and an ECU.Each tire sensor is configured to transmit an RF signal, which includesan identification signal associated with the respective tire sensor, andto detect an LF field. Each antenna is configured to transmit an LFfield to wake up two tire sensors. The RF receiver is configured toreceive the RF signals from the tire sensors after the tire sensors haveawakened. The ECU is in communication with the antennas, the receiverand the memory. The ECU is configured to receive the identificationsignals from the tire sensors via the receiver. The ECU is furtherconfigured to determine locations of the respective tire sensors basedon which antenna woke up the tire sensor transmitting the respectiveidentification signal and whether the identification signal matchesother received identification signals. The ECU is further configured tostore the identification signals in the memory with the identificationsignals being associated with the respective tire sensors thattransmitted the identification signal.

Another example of a method of localizing tire sensors on a vehicle topresent data to an operator of the vehicle includes transmitting an LFtire sensor wake up signal from four tire antennas to wake up tiresensors located in tires on the vehicle. Each antenna is configured andpositioned on the vehicle with respect to the tire sensors to transmitits respective tire sensor wake up signal to wake up two tire sensors.In response to receiving the tire sensor wake up signals, the method oflocalizing tire sensors further includes transmitting. RF signalsincluding an identification signal from tire sensors to an RF receiveron the vehicle. The method further includes receiving the RF signalsincluding the identification signal via the RF receiver into the ECU andcomparing the received identification signals. The method furtherincludes determining locations of the respective tire sensors based onwhich antenna woke up the tire sensor transmitting the respectiveidentification signal and whether the received respective identificationsignal matches other received identification signals. The method furtherincludes presenting tire data on a display at ignition ON and prior tomovement of the tires based on the received RF signals and thedetermined locations of the respective tire sensors. To aid inlocalizing the tire sensors, the method can further include memorizingthe identification signals by storing the identification signal and thecorresponding tire sensor in a memory that is in communication with theECU.

Another example of a tire pressure monitoring system that can overcomeat least one of the aforementioned shortcomings includes tire sensorsmounted in, on or adjacent respective tires of the vehicle, LF antennasmounted on the vehicle, and an ECU. Each tire sensor is configured totransmit an RF signal and to detect an LF field. Each antenna isconfigured to transmit an LF wake up field to wake up respective tiresensors. The ECU is in communication with the antenna, the tire sensorsand a radio configured to receive AM broadcast signals. The ECU cancommunicate with the radio to inhibit speakers in communication with theradio from emitting sound while each LF wake up field is beingtransmitted. The ECU can be configured to randomly send signals to theLF antennas to transmit respective tire sensor wake up fields.

A method for operating a tire pressure monitoring system on a vehiclehaving a radio includes transmitting an LF tire sensor wake up field towake up tire sensors. The tire sensors are disposed within tires mountedon the vehicle. The method further includes inhibiting sound from beingemitted from speakers receiving signals from a vehicle radio whiletransmitting the LF tire sensor wake up field. The method could also oralternatively include randomly transmitting LF tire sensor wake upfields to wake up tire sensors disposed within tires mounted on avehicle.

Another example of vehicle system that can overcome at least some of theaforementioned shortcomings includes tire sensors mounted in, on oradjacent respective tires of the vehicle, LF antennas including adoor-mounted antenna on a door of the vehicle, a receiver mounted on thevehicle, a door switch associated with the door having the door-mountedantenna mounted thereto, and an ECU in communication with the antennas,the receiver and the door switch. Each tire sensor is configured totransmit a signal and to detect an LF field. Each LF antenna isconfigured to transmit an LF tire sensor wake up field to wake uprespective tire sensors. The receiver is configured to receive signalstransmitted from the tire sensors. The door switch is configured fordetermining whether the door is open. The ECU is configured to receiveidentification signals from the respective tire sensors via the RFreceiver. The ECU is further configured to determine locations of therespective tire sensors based on which antenna woke up the tire sensortransmitting the respective identification signal and whether therespective identification signal matches other received identificationsignals. The ECU is further configured to: (1) disregard signals fromthe tire sensors woken up by the door-mounted antenna when the door wasopen or (2) inhibit the door-mounted LF antenna from transmitting the LFfield to wake up the tire sensors when the door is open.

Another example of a method for operating a vehicle system includesreceiving a signal to transmit an LF field from a door-mounted LFantenna to wake up tire sensors disposed within tires mounted on avehicle, and determining whether a door, to which the door-mounted LFantenna is mounted, is open. Where the door is open, the method foroperating can further include disregarding the received signal totransmit the LF field. Where the door is closed, the method foroperating can further include transmitting the LF field from thedoor-mounted LF antenna.

Another example of a method for operating a vehicle system includestransmitting an LF tire sensor wake up field from four antennasincluding a door-mounted LF antenna to wake up tire sensors located intires on the vehicle and determining whether a door, to which thedoor-mounted LF antenna is mounted, is open. The method further includesin response to detecting the tire sensor wake up fields by respectivetire sensors, transmitting signals including an identification signalfrom the tire sensors to a receiver on the vehicle. Where the door isopen, the method can include disregarding the received signal from therespective tire sensors awakened by the door-mounted antenna. Where thedoor is closed, the method can further include receiving the respectivesignal including the respective identification signal from therespective tire sensors awakened by the door mounted-mounted antenna.

Another method for localizing tire sensors includes determining a wakeup field power, transmitting an LF wake up field having the wake upfield power from an LF antenna on the vehicle, receiving anidentification signal from each tire sensor awakened by the transmittedLF wake up field, and determining whether a desired number of tiresensors have woken up in response to the transmitted LF wake up fieldbased on the received identification signals. When the desired number oftire sensors have woken up, the method can further include recording theidentification signals received from the awakened tire sensors and therespective antennas that awoke the respective tire sensors. The methodfurther includes determining whether a desired number of antennas havetransmitted a respective LF wake up field. When the desired number ofantennas have transmitted a respective LF wake up field, the method canfurther include comparing the received identification signals anddetermining locations for the tire sensors based on which respectiveantenna woke up which respective tire sensor and whether the receivedidentification signals match other received identification signals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a vehicle including an SMART entry systemand a tire pressure monitoring system (“TPMS”).

FIG. 2 is a flow diagram depicting a method of operating a vehicleentry/tire pressure monitoring system, which can include a method oflocalizing tire sensors on a vehicle.

FIG. 3 is a schematic depicting data stored in a memory of the systemshown in FIG. 1.

FIG. 4 is a schematic view of a tire sensor depicted in FIG. 1.

FIG. 5, is a schematic view of the tire sensor and a tire depicted inFIG. 1.

FIG. 6 is a flow diagram depicting another method for operating avehicle entry/tire pressure monitoring system.

FIG. 7 is a schematic view of the vehicle shown in FIG. 1 with a dooropen and some of the components depicted in FIG. 1 have been omitted forclarity.

FIG. 8 is a flow diagram depicting a method for localizing a tire sensorwith the door to the vehicle being open.

FIG. 9 is a flow diagram depicting a method for localizing tire sensorson a vehicle.

FIG. 10 is another schematic view of a vehicle including an SMART entrysystem and a tire pressure monitoring system (“TPMS”).

DETAILED DESCRIPTION

Throughout the specification and claims, the following terms take themeanings explicitly associated herein, unless the context clearlydictates otherwise. As used herein, the term “or” is an inclusive “or”operator, and is equivalent to the term “and/or” unless the contextclearly dictates otherwise. The term “based on” is not exclusive andallows for being based on additional factors not described, unless thecontext clearly dictates otherwise. In addition, throughout thespecification and claims, the meaning of “a,” “an,” and “the” includeplural references. Moreover, reciting a number of components, e.g.“three antennas,” does not preclude the use of more than threecomponents, and unless the context clearly dictates otherwise, therecitation of a certain number of components should be construed as aminimum number of components. The descriptions and drawings herein aremerely illustrative and various modifications and changes can be made inthe structures and steps disclosed without departing from the presentdisclosure. Various identified components of a vehicle disclosed hereinare merely terms of art and may vary from one vehicle manufacturer toanother. The terms should not be deemed to limit the present disclosure.The drawings are shown for purposes of illustrating one or moreexemplary embodiments and are not for purposes of limiting the appendedclaims. All references to direction and position, unless otherwiseindicated, refer to the orientation of the vehicle componentsillustrated in the drawings and should not be construed as limiting theappended claims.

With reference to FIG. 1, a vehicle 10 including a vehicle entry/tirepressure monitoring system is shown. In this SMART entry system, anoperator of the vehicle carries a portable transmission/reception unit12, hereinafter referred to as a fob, that transmits signals to an RFreceiver 14 (two are shown in FIG. 1) found on the vehicle 10 to operatecertain systems of the vehicle including door locks as well as turningthe ignition ON. The fob 12, which could be any device capable ofreceiving and sending wireless signals, is woken up by detecting an LFfield, and in response to detecting the LF field transmits an RF signalto the RF receiver 14. The fob 12 detects an LF wake-up signal, e.g. anLF signal at about 125 KHz, and transmits reply signals to the receiver,e.g. a reply signal at about 315 MHz. The frequencies discussed hereinare merely examples, and the system can operate at other frequencies.

For vehicles that include SMART entry and TPMS, efficiencies can beachieved by combining components of these once separate systems. Withcontinued reference to FIG. 1, the TPMS portion of a vehicle entry/TPMSincludes a left front tire sensor 20 installed in a left front tire 22of the vehicle 10, a rear left tire sensor 24 installed in a rear lefttire 26 of the vehicle, a right front tire sensor 28 installed in aright front tire 30 of the vehicle and a right rear tire sensor 32installed in a right rear tire 34 of the vehicle. A spare tire sensor 36can be installed in a spare tire 38, which can be typically located in atrunk 42 of the vehicle 10. Each tire sensor can be configured to takeair pressure measurements for the respective tire. Each tire sensor canalso measure the air temperature inside the respective tire.Additionally, each tire sensor can include an accelerometer to determinewheel direction, and therefore, direction of rotation, which can allowfor a determination of which side of the vehicle the wheel is on. Eachtire sensor can also supply vehicle loading information. This data canbe sent to the RF receiver 14 via RF signals transmitted from therespective tire sensors. The vehicle 10 and the vehicle entry/TPMS canalso include a front low frequency (“LF”) antenna 50 mounted towards afront of the vehicle 10 (e.g., in the engine room), a rear LF antenna 52mounted towards a rear of the vehicle (e.g., on the rear bumper), a leftside LF antenna 54 mounted adjacent, in or on a left door 56 of thevehicle, and a right side antenna 58 mounted adjacent, in or on a rightdoor 62 of the vehicle. The vehicle 10 can also include a cabin LFantenna 64 and a trunk LF antenna 66.

The front antenna 50 is configured to transmit a front LF field 70 towake up the front tire sensors 20, 28. The rear LF antenna 52 isconfigured to transmit a rear LF field 72 to wake up the rear tiresensors 24, 32. The rear LF field 72 generated by the rear LF antenna 52can also be large enough to wake up the spare tire sensor 36 on thespare tire 38, which can be located in the trunk 42 or rear of thevehicle 10. The left side antenna 54 is configured to transmit a left LFfield 74 to wake up the left tire sensors 20, 24. The right side LFantenna is configured to transmit a right LF field 78 to wake up theright tire sensors 28, 32. The left LF field 74 and the right LF field78 can also be large, or powerful, enough to wake up the spare tiresensor 36. Each of the wake up fields can be about 125 KHz.

As was explained above, it can be desirable to combine components of aTPMS with components of a vehicle entry system such as a SMART system.In view of this, the front antenna 50 can be configured to transmit afront SMART entry LF search field 80 to wake up the fob 12. The rearantenna 52 can be configured to transmit a rear SMART entry LF searchfield 82 to wake up the fob 12. The side antennas 54 and 58 can also beconfigured to transmit a SMART entry LF search field 84, 86respectively, to wake up the fob 12, for example for receiving signalsfor keyless entry of the vehicle. Similarly, the cabin LF antenna 64 andthe trunk LF antenna 66 can also be configured to transmit SMART entryLF search fields (not shown) to wake up the fob 12. If desired, thetrunk LF antenna 66 can also transmit a wake up search field to wake upthe spare tire sensor 36, as well as the left rear tire sensor 24 andthe right rear tire sensor 32. These SMART entry search fields can beabout 125 KHz. The search fields and/or wake up fields depicted in FIG.1 are merely exemplary and can take other configurations.

The antennas 50, 52, 54 and 58 that are used to wake up the tire sensors20, 24, 28 and 32 can also be used to detect for the fob 12 when anoperator of the vehicle 10 is approaching the vehicle and the cabin 64and trunk 66 LF antennas can also be used to detect whether the fob iswithin the vehicle. The antennas 52, 54 and 58, as well as the frontantenna 50 if desired, in the embodiment depicted in FIG. 1 serve a dualpurpose of waking up the tire sensors 20, 24, 28 and 32 in addition topolling for the fob 12. Unlike many known TPMS systems, the antennas 50,52, 54 and 58 that wake up the tire sensors 20, 24, 28 and 32 are notlocated in the wheel wells, but instead are spaced from the wheel wells.The front antenna 50 and the rear antenna 52 can be generally centrallylocated with respect to the outboard sides of the vehicle 10.

The vehicle entry/TPMS also includes an ECU 90 in communication with thetire sensors 20, 24, 28, 32 via the RF receiver 14 and the LF antennas50, 52, 54 and 58. The ECU 90 is configured to receive uniqueidentification signals from the respective tire sensors and to determinelocations of the respective tire sensors based on which antenna woke upthe tire sensor transmitting the respective unique identification signaland whether the respective unique identification signal matches otherreceived unique identification signals. This allows the ECU 90 todetermine which sensor is providing data to the ECU so that the ECU canpresent the appropriate data to the operator of the vehicle on a display92 that is also in communication with the ECU.

FIG. 2 depicts a method for operating a vehicle entry/tire pressuremonitoring system, which can also include a method for localizing tiresensors on the vehicle to present data to an operator of the vehicle.Even though steps of the method are presented in a logical order in FIG.2, unless otherwise noted in the appended claims, the appended claimsshould not be limited to the order presented in FIG. 2 or in any of thefigures presented herein. At 100, a signal is received to transmit an LFfield from the antennas 50, 52, 54 and 58. The signal to transmit the LFfield can occur in response to receiving a signal from the fob 12, whichcan allow for the presentation of tire pressure data on the display 92at or nearly instantaneously after an ignition for the vehicle 10 isturned ON. Accordingly, prier to the operator ever moving the wheels 22,26, 30 and 34 of the vehicle 10, tire pressure data can be presented onthe display 92. The signal to transmit the LF field can also begenerated by the ECU 90, for example while the vehicle 10 is moving, theECU can detect the tire pressure of the tires without receiving anysignal from the fob 12.

At 102, LF tire sensor wake up fields, also referred to as tire sensorwake up signals, 70, 72, 74 and 78 are transmitted from the respectiveantennas 50, 52, 54 and 58 to wake up tire sensors 20, 24, 28 and 32located in tires 22, 26, 30 and 34 on the vehicle 10. Each LF field canbe transmitted sequentially to allow the respective awakened tiresensors 20, 24, 28 and 32 to send reply RF signals, which include anidentification signal that is unique to each tire sensor, to the RFreceiver 14 so that the ECU 90 can record which antenna woke up therespective tire sensor transmitting the identification signal. The RFsignals transmitted by each tire sensor can be at around 315 MHz,although the reply signal could be at another frequency. An example of atable that could be used to determine which antenna woke up a respectivetire sensor transmitting an identification signal is shown in FIG. 3.This data that has been received by the ECU 90 can be stored in a memory94 (FIG. 1) that is also in communication with the ECU. In FIG. 3, “ID”refers to the unique identification signal that was received by the ECU90, “LF,” “LR,” “RF,” “RR,” and “SP” refer to the respective uniqueidentifications for each of the tire sensors, “ANTENNA” refers to theantennas 50, 52, 54 and 58, and “FRONT,” “RIGHT,” “LEFT” and “REAR”refers to each antenna, respectively.

With reference back to FIG. 2, at 104, the tire sensors 20, 24, 28 and32 detect the LF fields 70, 72, 74 and 78 transmitted by the respectiveantennas 50, 52, 54 and 58. Since the fob 12 is also is capable ofdetecting LF fields, at 106, the LF field is also detected at the fob12. To conserve power consumption and battery life for each of the tiresensors 20, 24, 28 and 32 and the fob 12, the tire sensor wake up fields70, 72, 74 and 78 can include a unique header format.

At 108, each of the tire sensors 20, 24, 28 and 32 can partially awakento process the unique header format upon receiving the LF field.Similarly, at 108, the fob 12 can also partially awaken to process theunique header format. The unique header format is processed at 110 inthe tire sensors 20, 24, 28 and 32 and in the fob 12 if the fob islocated within the LF field.

A determination is made, at 112, whether the header format in the LFfield matches. If the LF field transmitted by any of the antennas 50,52, 54 or 58 is for waking up a respective tire sensor, then the uniqueheader format would match a predetermined header format that would berequired to fully awaken the tire sensors 20, 24, 28 and 32. However, ifthe LF field transmitted by any of the antennas 50, 52, 54 or 58 was towake up the tire sensors 20, 24, 28 and 32, then the fob 12 would alsopartially awake to process this unique header format; however, the fobwould enter a sleep mode, at 114, upon determining that the uniqueheader format in the LF tire sensor wake up field does not match apredetermined header format required to wake-up the fob. Accordingly, noreturn signal to the RF receiver is transmitted in response to receivinga tire sensor wake up signal by the fob 12. By only awakening to processthe unique header format, and going to sleep if the unique header formatdoes not match a predetermined header format, power consumption for thefob 12 can be reduced and battery life can be increased. In a similarmanner, if one of the antennas 50, 52, 54 or 58 were to transmit a SMARTentry search field, this SMART entry search field would include a uniqueheader format that would only fully awaken the fob 12 and would notfully awaken the tire sensors. Accordingly, the tire sensors wouldsimply partially awake to process the unique header format, at 110,determine that the unique header format does not match, at 112, andsince the unique header format was for a SMART entry polling, as opposedto wake up the tire sensors, the tire sensors would then enter back intoa sleep mode, at 114, thus conserving power and battery life. Moreover,in the illustrated example, the tire sensors take pressure readings ofthe tires and transmit the RF signals only when fully awake, thusconserving power.

Where the header format matches the predetermined header format, at 112,then the tire sensors 20, 24, 28 and 32 fully awaken at 116. At 118, RFSignals including a unique identification signal are transmitted fromthe tire sensors 20, 24, 28 and 32. At 122, the RF signals includingeach unique identification signal is received at the receiver 14 (FIG.1). At 124, the received unique identification signals are compared, forexample by using the table similar to that shown in FIG. 3. At 126,locations for each tire sensor are determined based on which antennawoke up the tire sensor transmitting the respective uniqueidentification signal and whether the respective unique identificationsignal matches other received unique identification signals. As seen inFIG. 3, since the unique identification LF was found in a reply signalafter being awakened by both the front antenna 50 and the left sideantenna 54 and the front LF field 70 and the left LF field 74 overlap,the unique identification signal associated with “LF” in the table atFIG. 3 can be determined to be associated with the left front tiresensor 20. This can be performed for each of the signals received inresponse to each of the wake up signals.

At 128, tire sensor data can be presented on the display 92. With theembodiment depicted in FIG. 2, the tire sensor data can be presented onthe display at ignition ON, which should be construed as nearlyinstantaneously after ignition ON, and prior to movement of the tires22, 26, 30 and 34 based on the RF signals received from the respectivetire sensors and the determined locations of the respective tiresensors.

As mentioned above, it can be desirable to provide tire pressure data atignition ON on the display 92. Presenting the data at ignition ON shouldalso be construed as presenting the data nearly instantaneously afterignition ON, e.g. allowing enough time for the system, including thedisplay 92 and the ECU 90 to boot up and process the signals.Accordingly, it is desirable to locate the tire sensors prior to movingthe tires. However, since each tire sensor can be located in nearly aninfinite number of locations with respect to the antenna that is to wakeup the respective tire sensor (because the sensor is fixed to the tire,which rotates), the exemplary vehicle entry/tire pressure monitoringsystem employs four antennas (although more could be provided) toincrease the likelihood of awakening each tire sensor with at least oneof the LF wake up fields being provided by the respective antennas.

For example, with reference back to FIG. 1, the left side antenna 54 canmount to a left side sill (not shown) of the vehicle 10 beneath the leftdoor 56, on the left door 56 or on the vehicle body near the left door.Since the left side LF antenna is also used to pole for the fob 12, itis desirable to locate the left side LF antenna near the left door sothat an operator of the vehicle approaching the left door is able tosend a signal to the RF receiver 14, via the fob 12, to unlock the doorafter having been awakened by the left side LF antenna. Similarly, theright side. LF antenna 58 can be mounted to a right side sill of thevehicle beneath the right door 62, to the right door, or to the frame orvehicle body near the right door. Since the antennas 54 and 58 areremoved from the typical location of within the wheel well, awakeningthe left side and right side sensors with each of the antennas canpresent issues.

In the embodiment illustrated in FIG. 2 each tire sensor 20, 24, 28 and32 and each side antenna 54 and 58 are configured such that each tiresensor has at least about an 80% chance of being woken up by the left LFfield 74 or the right LF field 78. Again, this is because since each ofthe wheels rotate and each of the tire sensors is fixed to each of thewheels the location of the tire sensor with respect to the side antennas54 and 58 can change. This makes detection of each tire sensor moredifficult as compared to with an antenna located in the wheel well usedto wake up the respective tire sensor. To increase the likelihood ofwaking up each of the tire sensors, the front LF antenna 50 and the rearLF antenna 52 are provided. Since these antennas transmit respective LFfields 70 and 72 that overlap the side LF fields 74 and 78, thelikelihood of waking up each of the tire sensors is increased.Accordingly, each tire sensor 20, 24, 28 and 32, the front antenna 50,and the rear antenna 52 are configured, in combination with the sideantennas 54 and 58, such that each tire sensor has at least about a 95%chance of being woken up by the front LF field 70, the rear LF field 72,the left LF field 74, and the fight LF field 78.

There may be times when one of the antennas only awakens one tire sensoror no tire sensors. In order to provide localization of the tires atignition ON, further measures can be taken.

FIG. 4 schematically depicts each tire sensor 20, 24, 28 and 32. Eachtire sensor generally includes a power source or battery 140. Thebattery 140 provides power to a parameter sensor, such as a pressuresensor 142, a tire sensor controller 144, a receiver 146 and atransmitter 148. If desired, the receiver 146 and transmitter 148 can becombined in a transceiver. Each tire sensor also includes a receivedsignal strength indication (“RSSI”) circuit 152, which can further aidin localization of the tire sensors. The receiver 146 includes anantenna 154 that is configured to detect an LF field. The RSSI circuit152 generates RSSI data that is a function of radiated power fromrespective LF fields being picked up by the receiving antenna 154. Thetransmitter 148 can also include an antenna 156 that is configured totransmit an RF signal.

Localizing the tire sensors 20, 24, 28 and 32 using RSSI data can followmuch of the same process described above with reference to FIG. 2.Accordingly, when the tire sensor is fully awakened, at 116, the LFfield received through the antenna 154 and the receiver 146 can beprocessed, at 158, by the RSSI circuit 152 on the tire sensor todetermine the signal strength of the LF field. Each tire sensor can thentransmit an RF signal, including the RSSI data, via the transmitter 148and the antenna 156, at 118, back to the RF receiver 14 on the vehicle(118 in FIG. 2). At 122 in FIG. 2, the RF signal including the RSSI datais received at the RF receiver 14 and the RSSI data can be processed, at160, to determine locations of the respective tires based on the RSSIdata. For example, front antenna 50 can be located nearer the left fronttire sensor 20 as compared to the right front tire sensor 28.Accordingly, the LF field picked up by the left front tire sensor 20should be greater than the LF field picked up by the right front tiresensor 28. Accordingly, the RSSI data can further provide indicationswith regard to location of the respective tire sensors. The RSSI datacan be used in addition to the unique identifications, described above,to locate the tire sensors. Accordingly, if one of the antennas fails towake up a respective tire sensor, e.g. one of the blocks in the tableshown in FIG. 3 is missing, the RSSI data can be used to determine whichsensors have sent signals to the receiver 14.

As mentioned above, each tire sensor and each side antenna 54, 58 areconfigured such that each tire sensor can have about an 80% chance ofbeing woken up by the left LF field 74 or the right LF field 78 when thetires are not moving. To increase the likelihood that each tire sensoris woken up by a side antenna (the left side antenna 54 or the rightside antenna 58) or a centrally located antenna (the front antenna 50 orthe rear antenna 52), as seen in FIG. 5, the receiving antenna 154 canbe a two-axis antenna, which increases the likelihood of picking up anLF field, as compared to a standard one-axis antenna.

The two-axis receiver antenna 154 can include a first coil 162 wrappedaround a first axis 164 and a second coil 166 wrapped around a secondaxis 168. The first coil 162 and the first coil axis 164 are arranged tooptimize the likelihood of detecting the LF field generated from eitherthe front antenna 50 or the rear antenna 52 depending on the location ofthe tire sensor, i.e., whether the tire sensor is a front tire sensor ora rear tire sensor. As seen in FIG. 1, the front antenna 50 and the rearantenna 52 can be located nearer a longitudinal centerline of thevehicle 10 as compared to an outboard side of the vehicle. The firstcoil axis 164 can be arranged in a plane that is normal to a secondplane, which is normal to a rotational axis of the tire carrying thetire sensor. This allows the first axis 164 to align generally with therotational axis of the wheel, although the axis may be offset from therotational axis because of mounting constraints within the tire as wellas to optimize the likelihood of detecting the LF field being generatedfrom either the front antenna 50 or the rear antenna 52. Accordingly,the first axis 164 can be arranged generally transverse to thelongitudinal centerline of the vehicle 10. The second coil 166 and thesecond coil axis 168 are arranged to optimize the likelihood ofdetecting the LF field generated from either side antenna 54 or 58depending on the location of the tire sensor, i.e. whether the tiresensor is a left tire sensor or a right tire sensor. As seen in FIG. 1,the side antennas 54 and 58 are located nearer the outboard side of thevehicle as compared to the longitudinal centerline of the vehicle 10.The second coil axis 168 can be arranged in the second plane, which wasdescribed above as generally normal to the rotational axis of the tirecarrying the tire sensor. This allows the second axis 168 to aligngenerally with the traveling or longitudinal direction of the vehicle10, although the axis may be offset from the longitudinal axis becauseof mounting constraints within the tire as well as to optimize thelikelihood of detecting the LF field being generated from either theleft antenna 54 or the right antenna 58. Accordingly, the second axis168 can be arranged generally parallel with the longitudinal centerlineof the vehicle 10. As also explained above, each LF antenna, or at leastone of the LF antennas, can be positioned closer to one of the twosensors that are to be awakened by the LF field generated by the LFantenna. The ECU is then configured to determine locations of therespective tires based on RSSI data from the RF signals being receivedfrom the tire sensors.

The ECU 90 can also store identification signals in the memory 94 withthe identification signals being associated with the respective tiresensors, which can also aid in localization of the tire sensors. In theillustrated embodiment, the ECU 90 is configured to store theidentification signals received from the tire sensors in the memory 94in response to an ignition of the vehicle 10 being turned OFF. Bystoring the identification signals and associating the identificationsignals with respective tire sensors, at ignition OFF, should one of thetire sensors be undetectable when a wake up signal is being sent priorto ignition ON, the stored identification signals can be useful inlocalizing the tires. If the RF receiver 14 does not receive adequatedata in the RF signal or does not receive an RF signal from enough ofthe tire sensors to determine locations for the tire sensors, then thedisplay can present data associated with RF signals transmitted by thetire sensors in different manners. For example, the data presented onthe display 92 can be presented in a first state where the RF signalssent from the respective tire sensors 20, 24, 28 and 32 providesufficient data to the ECU 90 to determine a location for the respectivesensor. This data can be presented, for example, in a non-blinkingstate. The data can be presented in a second state, e.g. blinking, whenthe ECU 90 is unable to determine a location for the tire sensor basedon the received RF signals.

With reference back to FIG. 2, at 170, it can be determined whether theignition for the vehicle has turned OFF. If the ignition for the vehicle10 has turned OFF at 170, then at 172, the ECU can memorize thelocations of the tire sensors by storing data in the memory 94 similarto the table shown in FIG. 3. If the ignition is not turned OFF at 170,then the process can revert to waiting to receive a signal to transmitan LF field, at 100, which can come from the fob 12 or the ECU 90. Bymemorizing the location of the tire sensors 20, 24, 28 and 32 atignition OFF, assumptions can be made that the RF signals received fromthe respective tire sensors that include the ID signals will match thestored ID signals. For example, if not all of the antennas awakened eachof the tire sensors assigned to a respective antenna, per the tableshown in FIG. 3, but some of the received unique identification signalsmatched some of the stored unique identification signals, thenlocalization of the tire sensors can be determined. If, however, thetires have been changed on the vehicle, this will not be the case andthe localization of the tires will follow the process outlined in FIG.2. However, if some (fewer than three or four) of the tire sensors sendsback a signal that matches one stored in the memory, then the locationof the tire pressure sensors can be determined based on matching storedidentification signals associated with tire sensors and measurements canbe made for the tires and presented to the operator on the display 92.Additionally, if a respective tire sensor does not detect an LF wake upfield from two LF antennas, (perhaps the tire sensor only is awakened byonly one LF antenna), then by using the data stored in the memory 94 thelocation for this tire sensor can be deduced by comparing the replysignals from other tire sensors and the respective antennas that awokethe other tire sensors.

With reference back to FIG. 1, the vehicle 10 can also include a radio190 configured to receive AM broadcast signals via a receiver antenna192. The LF antennas 50, 52, 54 and 58 transmit an LF field that can bepicked up by the antenna 192. Accordingly, the ECU 90 communicates withthe radio 190 to inhibit speakers 194 that are in communication with theradio 190 from emitting sound while the LF field to wake up the tiresensors 20, 24, 28 and 32 or the key fob 12 is being transmitted. Theradio 190 can be configured to boot up in response to the radio being ONand the ignition of the car being ON. A time period for booting up theradio can be enlarged during transmission of the LF field to wake up thetire sensors. For example, at ignition ON a signal can be transmittedfrom the ECU 90 to the LF antennas 50, 52, 54 and 58 to transmit wake upfields to the respective tire sensors 20, 24, 28 and 32, A time periodfor booting up the radio can be enlarged during transmission of the LFfield so that the antenna 192 for the radio 190 does not pick up the LFfield resulting in undesirable output over the speakers 194.

Accordingly, a method for operating a tire pressure monitoring systemand a vehicle radio can include transmitting an LF tire sensor wakeupfield to wake up tire sensors disposed within tires mounted on avehicle, and inhibiting sound from being emitted by speakers receivingsignals from the vehicle radio while transmitting the wakeup field. Withreference back to FIG. 2, at 100, the signal is received to transmit theLF field, either to wake up the tire sensors 20, 24, 28 and 32, or evento poll for the fob 12. At 180, it can be determined whether the radiois ON (or set to receive AM broadcast signals). If it is determined thatthe radio is ON (or set to receive AM broadcast signals), then no outputfrom the radio 190 to the speakers 194 is permitted while the LF fieldsare being transmitted. The wake up or search process can then resume. Ifthe radio is OFF (or not set to receive AM broadcast signals), then theprocess can resume and transmit LF fields at 102. Alternatively, the ECU90 can receive communications from the radio 190, via a communicationarea network, stating that the radio was set to pick up AM broadcastsignals and to output sound to the speakers 194. If the ECU detects theradio is set to AM mode, then LF fields transmitted by the antennas 50,52, 54 and 58 can be randomly dispersed. In view of this, the system canfurther include a random number generator (not depicted in the figures,but can be located on hardware of the ECU or in software stored on theECU) in communication with the ECU 90. The ECU 90 can be configured torandomly generate signals to the LF antennas 50, 52, 54 and 58 totransmit respective tire sensor wake up fields based on output receivedfrom the random number generator or other similar method known in theart. The random number generator can be a hardware random numbergenerator or a software (pseudo) random number generator. If the LF wakeup fields transmitted by the antennas 50, 52, 54 and 58 happen to bepicked up by the receiver antenna 192 and were output to the speakers194, the LF wake up fields would sound like random noise to the operatorof the vehicle 10, which can be common while listening to AM radio.

As mentioned above, side antennas 54 and 58 can each mount to arespective door. Generating an LF field wakeup signal for the side tiresensors from an LF antenna on a door that is open could present problemsin that the door antenna may not wake up the desired tire sensors due toits change in position with respect to the tire sensors. Such asituation can be accommodated by providing a door switch 208 (only onedoor switch is shown in FIG. 1, however, one door switch can be providedwith each door or closure of the vehicle) that is in communication withthe ECU 90.

With reference to FIG. 6, at 210, a signal is received to transmit aleft side LF field from the left LF antenna 54, which is mounted to theleft door 56. It is at this stage where the process can follow twodifferent paths. Along one path, a determination is made as to whetherthe left door is open, at 212. If the left door is not open, at 212,then, at 214, the left side LF field is transmitted and, at 216, the RFreceiver 14 can receive the tire sensor unique identifications and theECU 90 can record the tire sensor unique identifications for tiresensors awakened by the left side LF field. If it is determined, at 212,that the left door is open, then the ECU 90, which could receive thesignal to transmit the left side LF field from the fob 12, disregardsthe received signal to transmit and moves on with the process toreceiving a signal to transmit the right side LF field, at 218.Alternatively, upon receiving the signal to transmit the left side LFfield, at 210, at 220, the left LF antenna 54 could transmit the leftside LF field. Then a determination can be made, at 222, as to whetherthe left door 56 is open. If the left door is not open, at 222, then theprocess moves to 216 and receives and records tire sensor IDs for tiresensor awakened by the left side LF field. If the left door is open, at222, then the RF receiver 14 can receive signals, at 224, from the tiresensors awakened by the left side LF field; however, any received tiresensor unique identifications are disregarded when the door is open.

A similar process is undertaken for the right LF antenna 58, which canbe mounted to the right door 62 of the vehicle 10. At 218, a signal isreceived to transmit a right side LF field from the right LF antenna 58,which is mounted to the right door 62. Similar to above, it is at thisstage where the process can follow two different paths. Along one path,a determination is made as to whether the right door is open, at 226. Ifthe right door is not open, at 226, then, at 228, the right side LFfield is transmitted and, at 230, the RF receiver 14 can receive thetire sensor unique identifications and the ECU 90 can record the tiresensor unique identifications for tire sensors awakened by the left sideLF field. If it is determined, at 226, that the right door is open, thenthe ECU 90, which could receive the signal to transmit the right side LFfield, disregards the received signal to transmit and moves on with theprocess to comparing received unique identification signals, at 232.Alternatively, upon receiving the signal to transmit the right side LFfield, at 218, the right LF antenna 58 could transmit the right side LFfield, at 234. Then a determination can be made, at 236, as to whetherthe right door 62 is open. If the right door is not open, at 236, thenthe process moves to 230 and receives and records tire sensor IDs fortire sensor awakened by the right side LF field. If the right door isopen, at 236, then the RF receiver 14 can receive signals, at 238, fromthe tire sensors awakened by the right side LF field; however, anyreceived tire sensor unique identifications are disregarded when thedoor is open and the process moves to compare received uniqueidentification signals at 232 and determining locations of the tiresensors at 240, which has been described in detail above with referenceto FIGS. 2 and 3. Alternatively, if it is detected that any of the doorsare open during transmission of the LF wake up field from the openeddoor, the process could also loop back so that the wake up field couldbe re-transmitted when the door is closed. This is only shown withregard to step 212 in FIG. 6; however, the loop back procedure can applyto steps 222, 226 and 236 also.

FIG. 7 depicts an alternative manner in which a tire sensor can belocalized, i.e. the location of the respective tire sensor can bedetermined, where a door to the vehicle is open. FIG. 7 depicts thevehicle 10 shown in FIG. 1 with the left door 56 open (shown inphantom). All of the components depicted in FIG. 1 can be found in thevehicle depicted in FIG. 7, but most have been omitted from FIG. 7 forclarity. The ECU 90 is configured to receive identification signals fromthe respective tire sensors 20, 24, 28 and 32 and to determine locationsof the respective tire sensor's based on which antenna woke up the tiresensor transmitting the respective identification signal and whether therespective identification signal matches other received identificationsignals. The ECU 90 is further configured to localize a respective tiresensor, e.g. the RF tire sensor 28 in FIG. 7, based on matchingidentification signals being transmitted to the receiver 14 from therespective tire sensor in response to the LF tire sensor wake up field74 (only a portion of the boundary of the wake up field 74 is shown inFIG. 7) from left side antenna 54, which is a door-mounted antenna, andthe LF tire sensor wake up field 78 from the right side antenna 58,which is located on an opposite side of the vehicle 10. When the leftdoor 56 is closed, the left LF wake up field 74 typically only awakensthe left front tire sensor 20 and the left rear tire sensor 26. However,with the left door 56 open, the left LF wake up field can be directed ina diagonal direction, with respect to the longitudinal axis of thevehicle, and wake up the right front tire sensor 28 in addition to theleft front tire sensor 20. In this example, the left rear tire sensor 26is not awakened by the left LF field 74 when the left door 56 is open.In view of this, the ECU can localize the right front tire sensor 28 bycomparing the received identification signals transmitted in response tothe LF wake up fields 74 and 78 with the left door 56 open. Eachreceived reply signal transmitted in response to the left side wake upfield 74 and the right side wake up field 78 can include theidentification of the right front tire sensor 28 when the left door 56is open. Accordingly, the location of the right front tire sensor 28 canbe determined.

A method for localizing tire sensors where a door having a door mountedantenna is open, will be described with reference to FIG. 8. The methodincludes, at 250, transmitting low frequency (“LF”) tire sensor wake upfields to wake up tire sensors located in tires on the vehicle. The LFtire sensor wake up fields can include a first LF tire sensor wake upfield from a door-mounted LF antenna mounted to a door on a first sideof the vehicle, e.g. the left side wake up field 74 shown in FIG. 7. TheLF tire sensor wake up fields can also include a second LF tire sensorwake up field from a second antenna mounted on a second, opposite, sideof the vehicle, e.g., the right side LF wake up field 78 in FIG. 7. Asmentioned above, the door-mounted antenna, e.g. the left side antenna54, is configured such that with the left door 56 being closed the leftLF tire sensor wake up field 74 is configured to wake up two tiresensors, i.e. the left front tire sensor 20 and the left rear tiresensor 26, located in respective tires on the first (left) side of thevehicle. The method further includes, at 252, determining whether thedoor to which the door-mounted LF antenna is mounted is open. If thedoor is not open, then, at 254, the tire sensors can be localized inmariners described above, e.g. by using the table shown in FIG. 3. Inother words, the process could return to step 124 in FIG. 2. Where thedoor is open, at 252, localizing a respective tire sensor can be basedon the respective identification signals received by the receiver 14(FIG. 1) in response to the first LF tire sensor wake up field, e.g. theleft LF field 74, and the second tire sensor wake up field, e.g. theright LF field 78, by, for example at 256, comparing the tire sensorswoken up by the left wake up field 74 and the tire sensors woken up bythe right wake up field 78. The received matching identification in thisexample would correspond to the right front tire sensor 28.

Learning tire sensor locations when in a vehicle manufacturing facilitycan present certain issues. Learning the location of the tire sensors atthe end of the manufacturing line can provide certain benefits later onto more quickly localize the tire sensor the next time the ignition tothe vehicle is turned ON. Locating the LF antennas away from the wheelwells, however, requires a higher power LF field to be generated to wakeup the wheel sensors as compared to if the LF antennas were locatedwithin the wheel well. This can cause problems, since the vehicles onthe assembly line are fairly close together. It may be possible that anLF wakeup field from an LF antenna on one vehicle might wake up the tiresensors located on an adjacent vehicle.

With reference to FIG. 9, a method for localizing tire sensors in afactory mode can include, at 300, setting or determining a power for anLF wakeup signal for waking up tire sensors on a vehicle. At 302, the LFfield is transmitted from an LF antenna. For example, the front LFantenna 50 transmits an LF field having a first power in an attempt towake up the front tire sensors 20 and 28. At 304, it is determinedwhether less than the desired number of tire sensors woke up. In thecase of transmitting an LF field from the front antenna 50, it isdetermined whether the LF field woke up two tire sensors. Determiningwhether the desired number of tire sensors have awakened can be based onwhether the RF receiver 14 receives the appropriate number of replysignals, e.g. two reply signals, from the respective tire sensors. Ifless than the desired number of tire sensors woke up, then at 306, thepower of the LF field is increased and the LF field can be retransmittedat 302. If, at 304, less than the desired number of tire sensors werenot woken up, then at 308, it is determined whether more than thedesired number of tire sensors have woken up in response to thetransmitted LF field. For example, if three or four tire sensors repliedwith an RF signal to the receiver 14 in response to the LF fieldgenerated by the front antenna 50, then there is a likelihood that tiresensors on an adjacent vehicle were woken up. If more than the desirednumber of tire sensors have woken up, then at 312, the power of the LFfield can be decreased and the LF field can be retransmitted at 302. Ifnot more than the desired number of tire sensors have woken up, then at314, the unique identifications received from the tire sensors can berecorded in the memory 92 that is associated with the ECU 90, as well asthe antenna that awoke the tire sensors. This information can be storedin a table, or similar organizational manner, as that shown in FIG. 3.At 316, a determination can be made as to whether all antennas havetransmitted wake up fields. If all antennas (or a desired number ofantennas) have not transmitted wake up fields, then the process moves tothe next antenna, at 318, to then determine the power of the LF field,at 300, and transmit the LF field, at 302. If all antennas (or thedesired number of antennas) have transmitted the wake up fields, then at320, the ECU can compare the received IDs and at 322, can determine thelocation of the tires similar to the manners described above.

The method for localizing tire sensors can include determining a wake upfield power, at 300, transmitting an LF wake up field having the wake upfield power from an LF antenna on the vehicle, at 302, receiving anidentification signal from each tire sensor awakened by the transmittedLF wake up field, and determining whether a desired number of tiresensors have woken up in response to the transmitted LF wake up fieldbased on the received identification signals, at 304. When the desirednumber of tire sensors have woken up, the method can further includerecording the identification signals received from the awakened tiresensors and the respective antennas that awoke the respective tiresensors, at 314. The method further includes determining whether adesired number of antennas have transmitted a respective LF wake upfield, at 316. When the desired number of antennas have transmitted arespective LF wake up field, the method can further include comparingthe received identification signals, at 320, and determining locationsfor the tire sensors; at 322, based on which respective antenna woke upwhich respective tire sensor and whether the received identificationsignals match other received identification signals. When less than thedesired number of tire sensors wake up, at 304, the wake up field powercan be increased, at 306. Another wake up field having an increased wakeup field power can be transmitted by returning to 302. Theidentification signals can be received from each tire sensor awakened bythe another wake up field and whether the desired number of tire sensorhave woken up in response to the transmitted another wake up field basedon the received identification signals can be determined at 304 and/or308. When more the desired number of tire sensors wake up, at 308, thewake up field power can be decreased, at 312. Another wake up fieldhaving a decreased wake up field power can be transmitted by returningto 302. The identification signals can be received from each tire sensorawakened by the another wake up field and whether the desired number oftire sensor have woken up in response to the transmitted another wake upfield based on the received identification signals can be determined at304 and/or 308. When less than the desired number of antennas havetransmitted a respective wake up field, at 316, another wake up fieldpower can be determined at 300, another wake up field having the anotherwake up field power can be transmitted at 302, and the identificationsignals from each tire sensor awakened by the another transmitted wakeup field can be received to determine if the desired number of tiresensor have woken up in response to the transmitted another wake upfield based on the received identification signals at 304 and/or 308.

RSSI data can also be used in determining the location of the tiresensors while in factory mode. By using RSSI data fewer than all four ofthe antennas 50, 52, 54 and 58 may have to transmit LF fields tolocalize the tire sensors. For example, where the side antennas arelocated closer to the front of the vehicle, the front sensors 20 and 28can transmit RSSI data to the receiver 14, after being awakened by therespective antennas 54 and 58, that indicates that a stronger LF fieldwas detected as compared to the LF signal detected by the rear tiresensors 24 and 32 and the spare tire sensor 36. In addition, incomparing the received unique identifications, at 320, the spare tiresensor 36 will transmit its unique identification in response to the LFfield transmitted by both the left antenna 54 and the right antenna 58.Accordingly, the localization of the spare tire sensor 36 can bedetermined.

The method can further include waking up individual tire sensors. Asmentioned above the LF antennas 50, 52, 54, 58 and 66 are not located ina wheel well of the vehicle. Each LF antenna can be mounted on thevehicle closer to a respective tire sensor as compared to other tiresensors. The method can include determining a wake up field power, at300, and transmitting an LF wake up field having the wake up field powerfrom an LF antenna on the vehicle to wake up tire sensors mounted withintires on the vehicle at 302. The method can further include, at 304 and308, determining whether a desired number of tire sensors have woken upbased on an identification signal being received from a respectiveawakened tire sensor by a receiver on the vehicle in response to the LFwake up field. At 314, the identification(s) received from the awakenedtire sensors can be recorded in the memory 92 that is associated withthe ECU 90, as well as the antenna that awoke the tire sensor(s). Themethod can, at 324, determine whether the desired number of tire sensorsthat was/were awakened was one tire sensor. Where the desired number oftire sensors that was/were awakened was one tire sensor, at 326, theawakened tire sensor can be localized based on the antenna that awakenedthe tire sensor. For example, if the front LF antenna 50 is locatednearer the left front tire sensor 20 and only one identification signalwas received in response to the front wake up field generated by thefront LF antenna, then the single identification signal received inresponse to the wake up field generated by the front LF antenna can beassociated with the left front tire sensor 20. If desired, the desirednumber can then be set to two tire sensors, at 328, and the method canproceed to step 306. This can provide further assurance for properlocation of the respective tire sensors.

The TPMS system described above can take other configurations usefulwhen combining TPMS with SMART entry. For example, FIG. 10 schematicallydepicts a vehicle 340 having LF antennas not located within the wheelwells, but located elsewhere on the vehicle as compared to where the LFantennas are shown in FIG. 1. The vehicle 340 depicted in FIG. 10 caninclude the same components as the vehicle 10 depicted in FIG. 1, andtherefore, for the sake of brevity only some of the components are shownin FIG. 10.

In the embodiment depicted in FIG. 10, the vehicle 340 can include aleft front low frequency (“LF”) antenna 350 mounted near a left frontcorner of the vehicle (e.g., on or near the front bumper), a left rearLF antenna 352 mounted near a left rear corner of the vehicle (e.g., onor near the rear bumper), a right front LF antenna 354 mounted near aright front corner of the vehicle (e.g., on or near the front bumper),and a right rear antenna 358 mounted adjacent near a right rear corner(e.g., on or near the rear bumper) of the vehicle. The vehicle 340 canalso include other LF antennas that are not shown.

The left front antenna 350 is configured to transmit a front LF field370 to wake up the front tire sensors 20, 28. The left rear LF antenna352 is configured to transmit a left rear LF field 372 to wake up therear tire sensors 24, 32. The left rear LF field 372 generated by theleft rear LF antenna 352 can also be large enough to wake up the sparetire sensor 36 (see FIG. 1) on the spare tire 38 (FIG. 1), which can belocated in the trunk 42. The right front antenna 354 is configured totransmit a right front LF field 374 to wake up the front tire sensors20, 24. The right rear LF antenna is configured to transmit a right rearLF field 378 to wake up the rear tire sensors 24, 32. The right rear LFfield 378 generated by the right rear LF antenna 358 can also be largeenough to wake up the spare tire sensor 36 (see FIG. 1) on the sparetire 38 (FIG. 1), which can be located in the trunk 42. Each of the wakeup fields can be about 125 KHz.

As was explained above, it can be desirable to combine components of aTPMS with components of a vehicle entry system such as a SMART system.In view of this, each antenna 350, 352, 354 and 358 can also beconfigured to transmit a SMART entry LF search field to wake up the fob12 (FIG. 1). The antennas 350, 352, 354 and 358 that are used to wake upthe tire sensors 20, 24, 28 and 32 can also be used to detect for thefob 12 when an operator of the vehicle is approaching the vehicle.

A vehicle entry/tire management system and methods of operating such asystem have been described above with particularity. Modifications andalterations will occur to those upon reading and understanding thepreceding detailed description. The invention is not limited to only theembodiments described above. Instead, the invention is broadly definedby the appended claims and the equivalents thereof.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives or varieties thereof, may bedesirably combined into many other different systems or applications.Also that various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

The invention claimed is:
 1. A tire pressure monitoring systemcomprising: tire sensors mounted in, on or adjacent respective tires ofa vehicle, each tire sensor being configured to transmit an RF signaland to detect an LF field; LF antennas mounted on the vehicle, theantennas being configured to transmit a low frequency (“LF”) tire sensorwake up field to wake up respective tire sensors; and an electroniccontrol unit (“ECU”) in communication with the antennas, the tiresensors and a radio configured to receive AM broadcast signals, whereinthe ECU communicates with the radio to inhibit speakers in communicationwith the radio from emitting sound while the LF tire sensor wake upfields are being transmitted.
 2. The system of claim 1, wherein theradio is configured to boot up in response to the radio being ON and anignition of the car being ON, wherein a time period for booting up theradio is enlarged during transmission of the LF wake up fields.
 3. Thesystem of claim 2, wherein the ECU detects whether the radio is set toan AM mode, and where the radio is set to an AM mode the ECUcommunicates with the radio to enlarge the time period for booting upthe radio to allow for transmission of the LF wake up fields beforesounds are emitted from the speakers.
 4. The system of claim 1, whereinthe ECU detects whether the radio is set to an AM mode, and where theradio is set to an AM mode the ECU communicates with the radio to muteoutput from the speakers while the LF tire sensor wake up fields arebeing transmitted.
 5. The system of claim 1, wherein the LF wake upfields are capable of being picked up by an AM antenna for the radio. 6.The system of claim 1, wherein the LF antenna is configured to transmitan LF portable transmission/reception unit wake up field to wake up aportable transmission/reception unit for keyless entry of the vehicleand the LF portable transmission/reception unit wake up field is capableof being picked up by an AM antenna for the radio.
 7. The system ofclaim 6, wherein the ECU detects whether the radio is set to an AM mode,and where the radio is set to an AM mode the ECU communicates with theradio to mute output from the speakers while the portabletransmission/reception unit for keyless entry of the vehicle is beingtransmitted.
 8. The system of claim 1, wherein the LF antennas include aleft front LF antenna mounted near a left front corner of the vehicle, aleft rear LF antenna mounted near a left rear corner of the vehicle, aright front LF antenna mounted near a right front corner of the vehicle,and a right rear LF antenna mounted near a right rear corner of thevehicle.
 9. The system of claim 8, wherein the tire sensors include aleft front tire sensor, a left rear tire sensor, a right front tiresensor and a right rear tire sensor, wherein the left front antenna isconfigured to transmit a left front LF field to wake up the front tiresensors, the left rear antenna is configured to transmit a left rear LFfield to wake up the rear tire sensors, the right front antenna isconfigured to transmit a right front LF field to wake up the front tiresensors, and the right rear antenna is configured to transmit a rightrear LF field to wake up the rear tire sensors.
 10. The system of claim1, wherein the LF antennas include a front LF antenna mounted towards afront of the vehicle, a rear LF antenna mounted towards a rear of thevehicle, a left side LF antenna mounted adjacent, in or on a left doorof the vehicle, and a right side LF antenna mounted adjacent, in or on aright door of the vehicle.
 11. The system of claim 10, wherein the tiresensors include a left front tire sensor, a left rear tire sensor, aright front tire sensor and a right rear tire sensor, wherein the frontantenna is configured to transmit a front LF field to wake up the fronttire sensors, the rear antenna is configured to transmit a rear LF fieldto wake up the rear tire sensors, the left antenna is configured totransmit a left LF field to wake up the left tire sensors, and the rightantenna is configured to transmit a right LF field to wake up the righttire sensors.
 12. A method for operating a tire pressure monitoringsystem and a vehicle radio, the method comprising: transmitting a lowfrequency (“LF”) tire sensor wake up field to wake up tire sensorsdisposed within tires mounted on a vehicle; and inhibiting sound frombeing emitted from speakers receiving signals from a vehicle radio whiletransmitting the LF tire sensor wake up field.
 13. The method of claim12, wherein inhibiting sound includes delaying boot up of the radio atignition ON while transmitting the LF tire sensor wake up field.
 14. Themethod of claim 12, wherein inhibiting sound includes muting thespeakers in communication with radio while transmitting the LF tiresensor wake up field.
 15. The method of claim 12, further comprisingtransmitting an LF portable transmission/reception unit wake up field towake up a portable transmission/reception unit for keyless entry of thevehicle, wherein inhibiting sound includes inhibiting sound from beingemitted from speakers receiving signals from a vehicle radio whiletransmitting the LF portable transmission/reception unit wake up field.16. The method of claim 15, wherein inhibiting sound includes delayingboot up of the radio at ignition ON while transmitting the LF portabletransmission/reception unit wake up field to wake up a portabletransmission/reception unit for keyless entry of the vehicle.
 17. Themethod of claim 15, wherein inhibiting sound includes muting thespeakers in communication with radio while transmitting the LF portabletransmission/reception unit wake up field to wake up a portabletransmission/reception unit for keyless entry of the vehicle.